The ultimate R version of Volkswagen's GTI was recently spied undergoing high-performance testing.

Don't let the diesel TDI badge fool you — the big center-mounted dual exhausts and beefed-up brakes suggest this is a much more fiery version of VW's hot-hatch.

The heart of this beast is a pumped-up 2.0T turbocharged four-cylinder with around 270 horsepower, connected to 4Motion all-wheel drive through a manual or dual-clutch-automatic six-speed transmission.

Acceleration from zero to 60 MPH should tick by in 5.5 seconds or less, with a top speed around 150 MPH.